Wearable computing systems and devices are an emerging category of consumer products. These devices enable users to perform a variety of tasks. For example, users may virtually interact with online account; record and/or observe information such as videos, images, and sounds; control other computing systems and other connected appliance; interact with other people; and in some instances monitor the current conditions of an individual's body.
Devices capable of monitoring an individual's fitness are becoming increasingly popular. Monitoring and maintaining physical fitness is an ongoing concern for individuals with busy lifestyles, and this concern is becoming more pronounced with an aging population. As a result, demand is increasing for devices that can track physical activities and individual fitness.
Various types of devices can be used to track an individual's physiological responses to various activities, such as exercise. While some devices are limited to use in laboratories and hospitals, portable/wearable devices for tracking physiological responses are being developed that can be worn by individuals at various locations on the individual's body. Often, these wearable devices may be positioned at locations other than on the individual's chest, for example when tracking muscle activity in various regions. Such devices may benefit from a method of determining an individual's heart rate that does not rely on the use of a chest strap or transthoracic measurements in general.